Cast steel members used in thermal power equipment, nuclear power equipment or the like are kept at high temperature and high pressure conditions for a long time in many cases, and therefore such equipment suffers creep damage due to thermal stress which in turn has generates cracks as a cause thereof.
Repair of such cracks are commonly carried out by a method including scraping parts adjacent the crack surface, hardfacing thereon and performing heat treatment. PTL 1, for example, discloses a case of repairing a turbine blade surface by forming a cutting surface to the surface crack, heating the surroundings of this cutting surface, welding and hardfacing the heated cutting surface with a welding material such as nickel base alloy, cutting the built up part after cooling and performing heat treatment to precipitate a gamma prime (γ′) phase.